Showing Usage

sub ShowUsage
{
print STDOUT << "EOF";

GD UXMON actmon monitoring package
Activity monitoring utility

usage: $0 [-h | --help]  [-c | --config ] [-l | --logfile ] [-d | --debug ]

-c         : Configuration file to be used
--config   : Same as c
-l         : Logfile where the messages will be stored
--logfile  : Same as l
-h         : this (help) message
--help     : Same as h
-d         : debug mode
--debug    : Same as d


EOF


}

ShowUsage();

result:

GD UXMON actmon monitoring package
Activity monitoring utility

usage: C:/Users/liuweic/Documents/demo/perl.pl [-h | --help]  [-c | --config ] [-l | --logfile ] [-d | --debug ]

-c         : Configuration file to be used
--config   : Same as c
-l         : Logfile where the messages will be stored
--logfile  : Same as l
-h         : this (help) message
--help     : Same as h
-d         : debug mode
--debug    : Same as d

Note: $0 of line 8.